CH stretching vibrational overtone spectra of 1,3,5,7-cyclooctatetraene and 1,1,1-trichloroethane

Local mode frequencies, <(omega)over tilde >, and anharmonicities, <(omega)over tilde > x, are obtained from the Delta v(CH) = 2-7 spectral regions of 1,3,5,7-cyclooctatetraene (COT) and 1,1,1-trichloroethane. In 1,1,1-trichloroethane <(omega)over tilde > and <(omega)over tilde > x are used in conjunction with ab initio potential energy surfaces to calculate local mode anharmonicity-torsion coupling terms, delta(omega x) and frequency-torsion coupling terms, delta(omega). Blue-shifting of sterically hindered CH oscillators in 1,1,1-trichloroethane indicates nonbonded, through-space intramolecular interactions with Cl. Multiple, complex Fermi resonances are observed in 1,1,1-trichloroethane and in COT between local mode states and local mode/normal mode combination states. Intensities of vibrational overtone transitions are calculated in the range Delta v(CH) = 3-9 using ab initio dipole moment functions and the harmonically coupled anharmonic oscillator (HCAO) model. HCAO intensities are compared to experimental intensities at Delta v(CH) = 3.